The present invention relates to sinks, particularly to kitchen sinks that are set into work surfaces, and the like.
For ease of use, kitchen sinks are usually positioned below the height of work surfaces, so that the mouth of the sink is at the height of the work surface. A variety of materials have been used for the manufacture of sinks and of work-surfaces, with the preferred material combinations in different countries being usually a trade-off between performance and cost, with tradition and the availability of various raw materials affecting preferences.
One preferred material for the fabrication of work surfaces is natural stone, preferably granite or other hard stone, that may be ground down and polished to a smooth and attractive finish, and that is scratch-resistant and resistant to chemical attack from household cleaners, lemon juice and other fluids with which it may come in contact. Where natural stone is expensive, artificial laminates such as formica, on chip-board countertops are also widely used. Although artificial materials provide a wider range of colours and textures than stone, they are generally less hard wearing, and their preference is usually for economic reasons.
The properties required for sinks are generally different from that required by the surrounding work surfaces. Sinks are manufactured from materials that are formable into deep containers, and are generally required to be waterproof to the extent, that when plugged, can hold water for long periods of time without warping, rusting or leaking. Sinks have been made from enameled cast iron, and this provides a relatively cheap, scratch resistant material. If the enamel chips however, the iron may rust. Stainless steel sinks are rust-resistant and fairly chemical resistant. They may scratch though. Additionally, unless the work surface is itself made completely from stainless steel, the sink tends to contrast with the work surface material, and looks unnatural when mounted in wood or stone work-surfaces, and in wood-like or stone like formica. Ceramic sinks have many advantages in that they may be produced in a range of colours and shades, when glazed are chemical resistant and scratch resistant, and can be cast into a variety of shapes and forms. Usually casting sinks from ceramics offers slightly more flexibility in the design shape than the deep drawing techniques used for fabricating sinks stainless steel.
In chemical workstations, for laboratories, fume cupboards and manufacturing plants the choice of material for work surfaces and for sinks is determined by the particular application both work surfaces and sinks are required to resist corrosion from the particular chemicals that they may come into contact with, particularly by the expected presence or absence of organic solvents and the like.
In laboratories, particularly within fume cupboards, the sink may be integrally fabricated with the surrounding countertop, either cast together therewith, or deep drawn therefrom. In domestic applications, the work surface is generally designed to fit a space, and invariably the work surface and the sink are separate units, that are often fabricated from different materials.
In general a sink may be attached to a work surface in one of three ways: (i) below, (ii) above, (iii) flush with the work surface.
(i) This is an established manner for attaching enamel sinks below both formica and stone work surfaces, and is sometimes used with stainless steel sinks. A hole is fabricated in the work surface, and the sink is attached below the hole. Where a particularly thick work surface is used, a stepped hole may be fabricated therein, such that the sink may be mounted below a thinner layer than the full work-surface. One disadvantage of under-surface mounting of this type, is that the join at the mouth of the sink, below the work surface, often accumulates dirt and mold. This may be difficult to clean, unsightly and unhygienic.
(ii) Above mounting is particularly applicable for mounting stainless steel sinks within counter tops and similar work surfaces. Around the mouth of the sink, there is a lip which protrudes above the work surface, and is usually attached thereto with a water resistant adhesive/sealant. Above mounting is inherently unsuitable for ceramic sinks, as they usually have too great a wall thickness. Another disadvantage of this type of mounting is that liquids on the work surface will not flow into the sink, and this makes washing down the work surfaces more difficult. Stainless steel sinks that are integrally connected to draining boards, where the sink and draining board unit is above mounted to the work surface provides a useful and widespread solution for formica on chipboard counter tops, where the counter top is best protected from large amounts of water, and the cleaning of the counter top is performed using a damp sponge. Here, the countertop can be fitted to the available space, and a sink and drainer can be selected from a small range of available, prefabricated off-the-shelf options.
(iii) Some stainless steel sinks, have a lip around the mouth of the sink, that widens into a flange. Although such sinks may be mounted above or below the counter top as described above, a preferred manner for mounting such stainless steel sinks to stone work surfaces, that is also applicable for some other materials combinations, is by flush-mounting. Here, the opening in the work surface is accurately cut, and finished with a sloping edge, and the sink is inset into the opening, so that the flange is substantially parallel to the work surface of the counter top. The sink being fixed in place, by a sealing adhesive such as silicone. A disadvantage of flush mounting in this manner is that it is inapplicable to ceramic sinks, since these invariably have uneven mouth openings/non planar flanges due to the casting and firing process used in their manufacture. It will be appreciated that a small unevenness in the height of the sink opening will be accented when such a sink is surface mounted. For this reason, the surface mounting of ceramic sinks is unknown, and despite the many advantages of ceramic sinks, such as low material and fabrication costs compared to quality stainless steel, wide range of colours available, and good scratch and chemical resistance, their use is largely confined to wash-basins, which are typically pedestal mounted, or bracket mounted to the wall of bathrooms, the sink not being mounted within a countertop or work surface.
Where used in kitchens, ceramic sinks are only ever mounted under the countertop, with all the disadvantages discussed hereinabove. Recently, integrated ceramic sink and work surface units have been fabricated for use in bathrooms. Here, the sink and work surface unit comes in a standard width, usually 105 cm or 120 cm, suitable for fixing over a bathroom cupboard. Since ceramic materials are inherently brittle however, the larger and more unwieldy the casting, the more difficult it is to transport and breakages are common. Integrated sink-countertop units are not generally suitable for kitchens, since much larger work surfaces are needed, than the washbasin surrounds of a bathroom cupboard, and as discussed above, kitchen work surfaces are usually designed to fit the space available, and are not restricted to limited range of sizes.
Thus despite the desirability of a ceramic sink fitted into a counter top, so that the mouth of the sink is flush with the work-surface, because of the abovementioned fabrication problem of the mouth warping during the kiln treatment necessary to harden the ceramic, such sinks are unknown. The present invention is directed to provide a method of fabrication for such a sink, a method for its installment, and sinks of this type.
It is a aim of the present invention to provide a According to the present invention, there is provided a method for fabricating a flush mounted ceramic sink.
It is a further aim of the present invention to provide a method for converting an existing ceramic sink into a flush mountable one.
It is another aim of the present invention to provide a ceramic sink that is flush-mountable within a countertop.
It is yet a further aim of the present invention to provide a method for flush mounting a ceramic sink into a countertop.
In accordance with a first aspect of the invention there is provided a method of converting a prior art ceramic sink having a mouth opening above its base; the mouth opening being surrounded by a non planar lip having an outer rim; into a flush mountable ceramic sink, comprising the steps of: grinding the non planar lip of the sink flat to form a planar flange; grinding away the outer rim of the flange at an angle to the planar flange, so that the outer rim of the flange tapers inwards from the flange towards the base of the sink; applying a post grinding glaze, at least to the flange; and firing the post-grinding glaze.
In accordance with a second aspect of the invention, there is provided a method of making a flush mountable ceramic sink characterized by having a mouth opening into a planar flange surrounded by an outer rim, the method comprising the steps of: producing a green sink having a base with a mouth surrounded by a lip opposite the base, the lip being surrounded by an outer rim; drying said green sink; firing the green sink; allowing the fired sink to cool; grinding the lip of the sink flat to form a ground planar flange; grinding away the outer rim at an angle to the planar flange, so that the outer rim tapers from the flange inwards towards the bottom of the sink; applying a post grinding glaze at least to the flange, and firing the post-grinding glaze.
Optionally, the method includes the additional step of applying a glaze to the green sink, prior to the firing step.
Optionally the lip of the green sink is a wide lip having holes therethrough.
Preferably, an additional step of quality control is performed, to reject poorly processed sinks, prior to the grinding stages.
Optionally, the method includes the further step of making holes in the sink. Typically such holes includes at least some of the following holes selected from the list of plug holes, overflow holes, hot-water pipe holes, cold-water pipe holes, mixer-tap holes, soap dispenser hole and drinking water pipe hole.
Preferably, the method also includes an additional step of quality control, to reject poorly processed sinks.
Preferably, the grinding away of the outer rim of the mouth is at an angle of 75xc2x0 to 83xc2x0 to the flange, so that the outer rim of the sink slopes inwards therefrom towards the base of the sink.
In accordance with a third aspect of the invention, there is provided a flush mountable ceramic sink, manufactured in accordance with one of the above methods.
In accordance with a fourth aspect of the invention, the ceramic sink may be flush mounted within a countertop having a planar work surface, such that the planar flange of the sink is parallel to the work surface of the countertop, and is essentially coplanar therewith, and the invention is also provides a method of mounting the flush mountable ceramic sink described hereinabove within a hole in a countertop having a planar work surface so that the planar flange of the sink is essentially coplanar with the work surface.